11997990 has 64 divisors (see below), whose sum is σ = 32886720. Its totient is φ = 3110400.

The previous prime is 11997977. The next prime is 11997991. The reversal of 11997990 is 9979911.

11997990 = 208² + 209² + ... + 355².

11997990 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11997991) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9390 + ... + 10590.

It is an arithmetic number, because the mean of its divisors is an integer number (513855).

Almost surely, 2^11997990 is an apocalyptic number.

11997990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 11997990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16443360).

11997990 is an abundant number, since it is smaller than the sum of its proper divisors (20888730).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

11997990 is a wasteful number, since it uses less digits than its factorization.

11997990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1254 (or 1248 counting only the distinct ones).

The product of its (nonzero) digits is 45927, while the sum is 45.

The square root of 11997990 is about 3463.8114844778. The cubic root of 11997990 is about 228.9300651545.

It can be divided in two parts, 11 and 997990, that added together give a square (998001 = 999²).

The spelling of 11997990 in words is "eleven million, nine hundred ninety-seven thousand, nine hundred ninety".